DTC B279A-12: Engine Immobiliser System Circuit Short to Battery [06/2018 - 08/2020]: Procedure

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CHECK CONNECTION OF CONNECTOR

Turn the engine switch off.

Check that the connectors are properly connected to the ECM and ID code box (immobiliser code ECU).

Connectors are properly connected.

Result

Proceed to
OK
NG

Result:

CONNECT CONNECTORS PROPERLY

Result:

See step 2

CHECK WHETHER ENGINE STARTS

Check that the engine starts.

Engine starts normally.

Result

Proceed to
OK
NG

Result:

USE SIMULATION METHOD TO CHECK. Refer to HOW TO PROCEED WITH TROUBLESHOOTING [06/2018 - ]

Result:

See step 3

CHECK ECM (TERMINAL EFIO)

Measure the voltage according to the value(s) in the table below.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Component with harness connected (ID Code Box (Immobiliser Code ECU))

Standard Voltage

Tester Connection	Condition	Specified Condition
G52-4 (EFIO) - Body ground	Engine switch on (IG)	11 to 14 V

Result

Proceed to
OK
NG

Result:

See step 5

Result:

See step 4

CHECK ID CODE BOX (IMMOBILISER CODE ECU) (TERMINAL EFIO)

Using an oscilloscope, check the waveform.

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

*a	Component with harness connected (ID Code Box (Immobiliser Code ECU))	*b	Waveform
*c	Approximately 160 ms.	*d	Approximately 270 ms.

Tester Connection	Condition	Tool Setting	Specified Condition
G52-4 (EFIO) - Body ground	Within 3 seconds of engine start or within 3 seconds of engine switch turned on (IG) after cable disconnected and reconnected to battery	2 V/DIV., 500 ms./DIV.	Pulse generation (See waveform)

Result

Proceed to
OK
NG

Result:

REPLACE ECM. Refer to REMOVAL [06/2018 - 10/2019] , or refer to REMOVAL [10/2019 - 08/2021]

Result:

REPLACE ID CODE BOX (IMMOBILISER CODE ECU)

CHECK HARNESS AND CONNECTOR (ID CODE BOX (IMMOBILISER CODE ECU) - ECM)

Disconnect the A25 ECM connector.

Measure the resistance according to the value(s) in the table below.

Standard Resistance

Tester Connection	Condition	Specified Condition
G52-4 (EFIO) - A25-59 (IMI)	Always	Below 1 Ω

Result

Proceed to
OK
NG

Result:

REPLACE ECM. Refer to REMOVAL [06/2018 - 10/2019] , or refer to REMOVAL [10/2019 - 08/2021]

Result:

REPAIR OR REPLACE HARNESS OR CONNECTOR